Method for preparing porous copper alloy wick and product prepared by the same

ABSTRACT

The disclosure provides a preparation method of a porous copper alloy wick, including the steps of: a) preparing an electrolyte, which is an aqueous solution including 0.5-1.8 mol/L sulfuric acid and 0.1-0.5 mol/L copper sulfate; b) cleaning with a mixed solution of a surfactant and a basic compound, activating with dilute hydrochloric acid and then cleaning the surface of a copper alloy substrate; c) forming a porous structure on the substrate by electrodeposition on the treated substrate in the electrolyte; and d) washing with water, drying and then sintering the product obtained in step c). By the method of the disclosure, the porous structure with the specific arrangement, excellent capillary force and permeability can be directly obtained on the surface of the substrate, which is good for the transmission of the working liquid.

CROSS REFERENCE

This application is based upon and claims priority to Chinese Patent Application No. 201711136869.9, filed on Nov. 16, 2017, the entire contents thereof are incorporated herein by reference.

TECHNICAL FIELD

The disclosure relates to a porous wick structure of a vapor chamber, and particularly to a porous wick with though holes of a vapor chamber prepared by the soft template method and a method for preparing the same.

BACKGROUND

With the development of science and technology, electronic products tend to be miniaturized. As the functions of electronic products become more and more, heat-generating and dissipating components are more and more concentrated. Therefore, the heat dissipation of electronic products is an important issue in the process of product design and assembly.

The heat-dissipating components depending on the phase change such as a heat pipe, a vapor chamber, and so on, have been implemented, providing the guaranty for heat dissipation. As a result, the heat-dissipating components have created significant value and profits for manufacturers. The heat dissipation power of the heat-dissipating components such as the vapor chamber also needs to be further improved. CN103542749A discloses a biomimetic wick of the vapor chamber, and the wick structure is good for the transmission of working substance and improves the heat dissipation capacity of vapor chamber. However, due to the complicated structure, it needs complicated and expensive devices such as a photolithography device. CN106435665A discloses a wick structure with a natural multi-scale dendritic pin fin copper surface structure of a heat pipe or a vapor chamber prepared by electrochemical deposition, but the structure is easy to cause the working substance to be carried by the air flow, reducing heat dissipation efficiency. Moreover, the porous structure prepared by the electrochemical deposition has weak bonding force with the substrate, poor mechanical strength and the like, which presents a significant challenge to the reliability and longevity of the product.

SUMMARY

Provided herein is a method for preparing a porous copper alloy wick to overcome the above shortcomings and deficiencies. The method for preparing porous wick comprises the steps of: a) preparing an electrolyte, which is an aqueous solution comprising 0.5-1.8 mol/L sulfuric acid and 0.1-0.5 mol/L copper sulfate; b) cleaning the surface of a copper alloy substrate with a mixed solution of a surfactant and a basic compound, activating with dilute hydrochloric acid, and then rinsing; c) forming a porous structure on the substrate by electrodeposition on the treated substrate in the electrolyte; and d) washing with water, drying and then sintering the product obtained in step c).

The disclosure also provides a porous copper alloy wick prepared by the methods described above.

In the disclosure, the porous wick is prepared by the composite method of electrodeposition and sintering. The pure copper porous structure prepared by electrodeposition is rearranged by the nano effect after the treatment at a high temperature, and the structural strength is enhanced. The method of the disclosure can be applied to various shapes of heat pipe and vapor chamber products, and the thickness of the porous structure can be arbitrarily adjusted above 10 μm, which provides a new direction for the personalized design of the product. By the method of the disclosure, the porous structure with the specific arrangement, excellent capillary force and permeability can be directly obtained on the surface of the substrate, which is good for the transmission of the working liquid.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an SEM image of a cross section of a porous wick prepared in Example 1.

FIG. 1B is a Zn element distribution map of the porous wick prepared in Example 1.

FIG. 1C is a Cu element distribution map of the porous wick prepared in Example 1.

FIG. 1D is a compositional content distribution map of the porous wick prepared in Example 1.

FIG. 2A and FIG. 2B are SEM images of the porous wick prepared in Example 1 with different magnifications.

DETAILED DESCRIPTION

The disclosure is described in detail below in conjunction with specific embodiments. However, the protection scope of the disclosure is not limited to the following examples.

EXAMPLE 1

A certain amount of copper sulfate is weighed and dissolved in deionized water to form a copper sulfate solution, and then an appropriate amount of concentrated sulfuric acid is added to the copper sulfate solution to form an electrolyte of 0.5 mol/L sulfuric acid and 0.1 mol/L copper sulfate.

H70 brass is used as a substrate, and the substrate is washed with a mixed solution of a surfactant and a basic compound, activated with dilute hydrochloric acid, and then washed with deionized water.

The treated substrate is electrodeposited in the formed solution at a constant current density to form a porous structure on the substrate, wherein the electrodeposition temperature is 20° C., the constant current density is 0.5 A/cm², and the electrodeposition time is 10 minutes.

The substrate and its porous structure are washed with water, dried, and sintered in a vacuum sintering furnace at 450° C.

EXAMPLE 2

An electrolyte is prepared in the same manner as in Example 1 except that the concentration of sulfuric acid is 1.8 mol/L and the concentration of copper sulfate is 0.5 mol/L.

Iron brass is used as a substrate, and the substrate is pretreated in the same manner as in Example 1.

The treated substrate is electrodeposited in the formed solution at a constant current density to form a porous structure on the substrate, wherein the electrodeposition temperature is room temperature, the current density is 0.8 A/cm², and the time is 90 seconds.

The substrate and its porous structure are washed with water, dried and then sintered in a vacuum sintering furnace at 500° C.

EXAMPLE 3

An electrolyte is prepared in the same manner as in Example 1 except that the concentration of sulfuric acid is 1.0 mol/L and the concentration of copper sulfate is 0.2 mol/L.

Lead brass is used as a substrate, and the substrate is pretreated in the same manner as in Example 1.

The treated substrate is electrodeposited in the formed solution at a constant current density to form a porous structure on the substrate, wherein the electrodeposition temperature is 20° C., the current density is 1.5 A/cm², and the time is 50 seconds.

The substrate and its porous structure are washed with water, dried and then sintered in a vacuum sintering furnace at 600° C.

EXAMPLE 4

An electrolyte is prepared in the same manner as in Example 1 except that the concentration of sulfuric acid is 0.8 mol/L and the concentration of copper sulfate is 0.2 mol/L.

Aluminum brass is used as a substrate, and the substrate is pretreated in the same manner as in Example 1.

The treated substrate is electrodeposited in the formed solution at a constant current density to form a porous structure on the substrate, wherein the electrodeposition temperature is 20° C., the current density is 5 A/cm², and the time is 20 seconds.

The substrate and its porous structure are washed with water, dried and then sintered in a vacuum sintering furnace at 750° C.

EXAMPLE 5

An electrolyte is prepared in the same manner as in Example 1 except that the concentration of sulfuric acid is 0.7 mol/L and the concentration of copper sulfate is 0.3 mol/L.

H68 brass is used as a substrate, and the substrate is pretreated in the same manner as in Example 1.

The treated substrate is electrodeposited in the formed solution at a constant current density to form a porous structure on the substrate, wherein the electrodeposition temperature is 20° C., the current density is 1A/cm², and the time is 1 minute.

The substrate and its porous structure are washed with water, dried and then sintered in a vacuum sintering furnace at 700° C.

EXAMPLE 6

An electrolyte is prepared in the same manner as in Example 1 except that the concentration of sulfuric acid is 0.5 mol/L and the concentration of copper sulfate is 0.1 mol/L.

H70 brass is used as a substrate, and the substrate is pretreated in the same manner as in Example 1.

The treated substrate is electrodeposited in the formed solution by the decreasing current density to form a porous structure on the substrate, wherein the electrodeposition temperature is 20° C. , the initial current density is 0.5 A/cm², the current density decreasing speed is 0.05 A/cm²·s, and the deposition time is 10 seconds.

The substrate and its porous structure are washed with water, dried and then sintered in a vacuum sintering furnace at 450° C.

EXAMPLE 7

An electrolyte is prepared in the same manner as in Example 1 except that the concentration of sulfuric acid is 0.5 mol/L and the concentration of copper sulfate is 0.1 mol/L.

H70 brass is used as a substrate, and the substrate is pretreated in the same manner as in Example 1.

The treated substrate is electrodeposited in the formed solution by the decreasing current density to form a porous structure on the substrate, wherein the electrodeposition temperature is 20° C., the initial current density is 2 A/cm², the current density decreasing speed is 0.002 A/cm²·s, and the deposition time is 5 minutes.

The substrate and its porous structure are washed with water, dried and then sintered in a vacuum sintering furnace at 600° C.

EXAMPLE 8

An electrolyte is prepared in the same manner as in Example 1 except that the concentration of sulfuric acid is 0.5 mol/L and the concentration of copper sulfate is 0.1 mol/L.

H70 brass is used as a substrate, and the substrate is pretreated in the same manner as in Example 1.

The treated substrate is electrodeposited in the formed solution by the decreasing current density to form a porous structure on the substrate, wherein the electrodeposition temperature is 20° C., the initial current density is 5 A/cm², the current density decreasing speed is 0.001 A/cm²·s, and the deposition time is 10 minutes.

The substrate and its porous structure are washed with water, dried and then sintered in a vacuum sintering furnace at 450° C.

EXAMPLE 9

An electrolyte is prepared in the same manner as in Example 1 except that the concentration of sulfuric acid is 0.5 mol/L and the concentration of copper sulfate is 0.1 mol/L.

H70 brass is used as a substrate, and the substrate is pretreated in the same manner as in Example 1.

The treated substrate is electrodeposited in the formed solution by the increasing current density to form a porous structure on the substrate, wherein the electrodeposition temperature is 20° C., the initial current density is 0.01 A/cm², the current density increasing speed is 0.05 A/cm²·s, and the deposition time is 10 seconds.

The substrate and its porous structure are washed with water, dried and then sintered in a vacuum sintering furnace at 450° C.

EXAMPLE 10

An electrolyte is prepared in the same manner as in Example 1 except that the concentration of sulfuric acid is 0.5 mol/L and the concentration of copper sulfate is 0.1 mol/L.

H70 brass is used as a substrate, and the substrate is pretreated in the same manner as in Example 1.

The treated substrate is electrodeposited in the formed solution by the increasing current density to form a porous structure on the substrate, wherein the electrodeposition temperature is 20° C., the initial current density is 0.1 A/cm², the current density increasing speed is 0.001 A/cm²·s, and the deposition time is 10 minutes.

The substrate and its porous structure are washed with water, dried and then sintered in a vacuum sintering furnace at 450° C.

EXAMPLE 11

An electrolyte is prepared in the same manner as in Example 1 except that the concentration of sulfuric acid is 0.5 mol/L and the concentration of copper sulfate is 0.1 mol/L.

H70 brass is used as a substrate, and the substrate is pretreated in the same manner as in Example 1.

The treated substrate is electrodeposited in the formed solution by the increasing current density to form a porous structure on the substrate, wherein the electrodeposition temperature is 20° C., the initial current density is 0.2 A/cm², the current density increasing speed is 0.005 A/cm²·s, and the deposition time is 5 minutes.

The substrate and its porous structure are washed with water, dried and then sintered in a vacuum sintering furnace at 450° C.

FIG. 1A is an SEM image of a cross section of a porous wick prepared in Example 1. As can be seen from the figure, the light gray portion is the main structure of the wick. FIG. 1B shows the distribution of elemental zinc, in which white spots indicate the distribution and presence of the element. FIG. 1C shows the distribution of elemental copper, in which gray spots indicate the distribution and presence of the element. FIG. 1B and 1C illustrate that the porous wick is in the form of a copper-zinc alloy. FIG. 1D shows the compositional content of the structure, which indicate the existence of copper-zinc alloy. The above results prove that zinc atoms in the substrate diffuse into the porous structure to form a copper-zinc alloy by sintering. FIG. 2A and FIG. 2B are SEM images of the surface of the porous wick prepared in Example 1 with different magnifications. FIG. 2A shows the porous structure of the wick, and FIG. 2B shows that the prism structure appears on the surface, which proves that the zinc element diffusion in the substrate during sintering. As the zinc element in the substrate diffuses into the porous structure during sintering to form a copper-zinc alloy, the surface hydrophilicity of the porous structure is increased, thereby facilitating the transport of the working liquid in the porous structure to improve the heat dissipation efficiency.

For the other embodiments provided by the disclosure, the characteristics of the obtained produc are the same as or similar to those in Example 1, and are not described in detail herein.

Of course, the disclosure may have other various embodiments. Without departing from the spirit and essence of the disclosure, those skilled in the art can make various corresponding changes and modifications according to the disclosure, but these corresponding changes and variations shall fall within the scope of the appended claims of the disclosure. 

1. A method for preparing a porous copper alloy wick, comprising the steps of: a) preparing an electrolyte, which is an aqueous solution comprising 0.5-1.8 mol/L sulfuric acid and 0.1-0.5 mol/L copper sulfate; b) cleaning the surface of a copper alloy substrate with a mixed solution of a surfactant and a basic compound, activating with dilute hydrochloric acid, and then rinsing; c) forming a porous structure on the substrate by electrodeposition on the treated substrate in the electrolyte; and d) washing with water, drying, and then sintering the product obtained in step c).
 2. The method for preparing a porous copper alloy wick according to the claim 1, wherein the electrodeposition is carried out with a constant current density of 0.5-5 A/cm² for 20 seconds-10 minutes.
 3. The method for preparing a porous copper alloy wick according to the claim 2, wherein the constant current density is 0.8-1.5A /cm², and the electrodeposition time is 50-90 seconds.
 4. The method for preparing a porous copper alloy wick according to the claim 1, wherein the electrodeposition is carried out by the increasing current density, the initial current density is 0.01-0.1 A/cm², the current density increasing speed is 0.001-0.05 A/cm²·s, and the deposition time is 10 seconds-10 minutes.
 5. The method for preparing a porous copper alloy wick according to the claim 1, wherein the electrodeposition is carried out by the decreasing current density, the initial current density is 0.5-5 A/cm², the current density decreasing speed is 0.001-0.05 A/cm²·s, and the deposition time is 10 seconds-10 minutes.
 6. The method for preparing a porous copper alloy wick according to the claim 1, wherein the substrate is brass, tin brass, lead brass, aluminum brass, nickel brass or iron brass.
 7. The method for preparing a porous copper alloy wick according to the claim 1, wherein the sintering is carried out in a protective atmosphere, a reducing atmosphere or a vacuum atmosphere at a temperature of 450 to 750° C.
 8. The method for preparing a porous copper alloy wick according to the claim 7, wherein the protective atmosphere is at least one selected from nitrogen and argon and the reducing atmosphere is a mixture of nitrogen and hydrogen.
 9. A porous copper alloy wick, being prepared by the method according to claim
 1. 